driving normally when solid check engine light came on. drove immediately to autozone for code pull- p1121. did a brief lookup online but it looks like the 3 way control valve is stuck? based on my quick research this is an engine code that im fine to drive on? im hoping to daily drive it all next week and get the pcv valve replaced next weekend? secondary question: i also double checked to make sure my coolant wasn't low- i opened the coolant cap on the radiator and a splash of coolant came out (wasn't hot). the coolant was very close to thetop of the cap and i put the cap back on....did i introduce air into the coolant system by doing that? thanks for any and all insight!
My thought on your secondary question is you may have let a little air out. I wouldn't worry about that personally. PCV, positive crankcase ventilation, takes crank case vapors and feeds them into the air intake and into the combustion chamber. It's essentially for pollution control because when a cylinder fire, there is a small amount of pressure that escapes past the piston ring and into the crank case. If it gets stuck shut the pressure has to go somewhere... So you can drive, best case scenario you get bad gas mileage. Worst case scenario, you create and oil leak. Like a weak valve cover gasket could start leaking. It's really up to you. A pcv valve goes in the top of the valve cover and contains a spring causing it to only be open or closed. Kinda like a coolant thermostat does. P1121 is a 3 way coolant control valve and driving with it malfunctioning is ill advisable. If you overheat your ICE or the components of your hybrid system, the results will be very expensive repairs. Just because the coolant is full, doesn't means it's making it out of those hot high voltage components and into the radiator to cool. Which obviously means that the much cooler coolant from the radiator isn't making it inside to cool the components as intended. They extended the warranty and called it a warranty enhancement to 150k on those on the model years 04 - 11 I believe because it was a common known problem causing much bigger problems from my understanding. I believe the water pump was recalled as well because they are known to fail as well. Not a water pump like you would think of in a normal vehicle though. A small weak electric pump with a great big job... I hope I helped. Best of luck to you! Posted via the PriusChat mobile app.
There's quiet a bit of incorrect information here, I'll try to clear it up. Yes overheating the ICE, inverter, or transaxle would be bad but the 3-way coolant control valve won't cause any of that. The Prius has two completely separate cooling systems, one for the inverter/transaxle, and another for the combustion engine. The valve in question is part of the engine cooling system. The function of the 3-way control valve is to direct hot water from the engine to the heater core, coolant storage tank (CHST), or both. The CHST is used to keep coolant hot for engine pre heating. The heater core, well we know what that's for. The point is that you can restrict or stop coolant flow to either of these components and it won't have any effect on the coolant flowing thru the engine block and cylinder head. The warranty enhancement for the 3-way valve only applied in CARB states because they take emissions related equipment very seriously, not because it was causing other damage. So, driving around with a faulty 3-way valve could slightly increase fuel consumption when you first start the car or the heater might not work. Not much else. The real reason to fix this problem is because you shouldn't live with a check engine light even if you know it's nothing serious. If something serious does come up you won't know because the warning light was already on. I hope that helps.
Unlike some people, I appreciate being corrected! Thanks for clearing things up man. I prefer to error on the side of caution. Posted via the PriusChat mobile app.
I have trouble code p1121, but my gas mileage actually increased 1/10 mpg. Is this possible? Maybe the heater core is not getting heated and the heat is conserved for the engine instead, increasing efficiency.
I would consider 1/10 mpg to be statistically irrelevent. Regardless of the effect I would still fix it so the check engine light stays off. Posted via the PriusChat mobile app.
Ok maybe someone can answer this ... I have replaced all the components for this plus some it was working fine for like 3 weeks until yesterday and now it's got no heat a the p1121 code again what are we doing wrong
First check that the coolant level in the radiator is good. Next, what part did you put in? If it wasn't a Toyota part then I would suspect that the replacement had failed. (make sure that the wiring connector is fully seated). Posted via the PriusChat mobile app.
why does my scan tool say p1121 is a throttle position sensor voltage high? Is this because it is not a prius scanner specifically? Also, the dealership apparently replaced this part but the code still comes up, are they bsing me?
P0XXX codes are (theoretically) universal across all cars. P1XXX codes are manufacturer-specific, so they can mean one thing on car A and something totally different on car B.
Or even some other car entirely. As Leadfoot points out, P1 codes are assigned by manufacturers, so the same P1 code is allowed to mean completely different things to different manufacturers, and even in different car models from the same manufacturer. Manufacturer's choice. People get weird ideas of what a code is telling them either by using Google to look up a manufacturer's-choice code (and then not carefully eliminating the Google results that are not for exactly their car), or by using a generic scan tool that has some fortune cookies for codes built into it. In general, if you're using a scan tool that isn't Techstream and it doesn't know exactly what car model you've got, you are best off just writing down what the code is, and ignoring anything the tool tells you it means, and looking the code up in your car's repair manual. Toyota Service Information and Where To Find It | PriusChat It's a little different if you get a code in one of the "SAE defined" ranges. Those are supposed to mean (roughly) the same thing in any car. On the other hand, because of that, they are often super generic. You might find some code has an SAE fortune cookie like "Drive Motor A Performance", but Toyota calls their motors MG1 and MG2, and you may still need to check a Prius repair manual to find out which one they matched up with the SAE codes for "drive motor A" or "drive motor B". Keep in mind that even doing a search for the code on PriusChat is still dicey, because it will turn up all the posts by people who looked up their codes in Google and then posted about them here. But at least you will get a better signal-to-noise ratio searching here than you will by plain googling.
